Electric furnace installation

ABSTRACT

The roof of a top-charge direct arc melting furnace is supported from the superstructure of a gantry frame structure and, if desired, with the furnace back plate assembly serving as the pillar or upright frame member on one side of the furnace body. This gantry or bridge-like structure is supported on a support platform extending alongside the furnace body, and, in certain embodiments, fore-and-aft platform members on opposite sides of the furnace body are interconnected at their front ends by a cross member into a U-shaped platform. The support platform and gantry structure constitute an assembly which is tiltable independently of the furnace body when the roof of the furnace is lifted, so as to uncover the furnace, thereby permitting it to be charged from the top. Means are provided so as to detachably interlock the support platform of the roof supporting gantryplatform assembly with the furnace body so that with the roof closed the furnace body together with the roof tilt in unison, either rearwardly for slag removal or forwardly for pouring. As a safety feature, the interlock means also serves to lock the furnace body or shell to a fixed part of the furnace pit until such time as the furnace shell or body is fully interlocked with the gantry support platform. By reason of the foregoing construction a number of important advantages are provided in an electric furnace installation, one of them being that the center of gravity of the furnace body may be located so that it always tends to assume an upright position and not fall or tip over even when the roof is raised and moved from over the top of the furnace body. Elimination of severe cantilever loading to support the weight of the furnace roof may be accomplished in the new construction and a number of important advantages flow from this feature.

United States Patent 1 Ames [ 11 3,745,224 1 July 10, 1973 1 ELECTRIC FURNACE INSTALLATION [75] inventor: Victor B. Antes, Midlothian, Ill. [73] Assignee: Whiting Corporation, Harvey, 111.

[22] Filed: Oct. 20, 1971 [211 App]. No.: 190,950

[52] U.S. Cl. 13/10, 13/33 [51] Int. Cl. F27d 3/00, F27b 14/02 [58] Field of Search 13/10, 33

[56] References Cited UNITED STATES PATENTS 1,325,539 12/1919 Snyder 13/10X 2,886,617 5/1959 Sorg et al 13/10 2,944,100 7/1960 Sorg et al 13/10 Primary Examiner-Roy N. Envall, .lr. Attorney-Fred S. Lockwood et a1.

[ ABSTRACT The roof of a top-charge direct arc melting furnace is supported from the superstructure of a gantry frame structure and, if desired, with the furnace back plate assembly serving as the pillar or upright frame member on one side of the furnacebody. This gantry or bridgelike structure is supported on a support platform extending alongside the furnace body, and, in certain embodiments, fore-and-aft platform members on opposite sides of the furnace body are interconnected at their front ends by a cross member into a U-shaped platform. The support platform and gantry structure constitute an assembly which is tiltable independently of the furnace body when the roof of the furnace is lifted, so as to uncover the furnace, thereby permitting it to be charged from the top. Means are provided so as to detachably interlock the support platform of the roof supporting gantry-platform assembly with the furnace body so that with the roof closed the furnace body together with the roof tilt in unison, either rearwardly for slag removal or forwardly for pouring. As a safety feature, the interlock means also serves to lock the furnace body or shell to a fixed part of the furnace pit until such time as the furnace shell or body is fully interlocked with the gantry support platform.

By reason of the foregoing construction a number of important advantages are provided in an electric furnace installation, one of them being that the center of gravity of the furnace body may be located so that it always tends to assume an upright position and not fall or tip over even when the roof is raised and moved from over the top of the furnace body. Elimination of severe cantilever loading to suppo'i't the weight 'of the furnace roof may be accomplished in the new construction and a number of important advantages flow from this feature.

25 Claims, 19 Drawing Figures Patented July 10, 1973 3,745,224

8 Sheets-Sheet 1 Patented July 10, 1973 8 Sheets-Sheet 2 Patented July 10, 1973 8 Sheets-Sheet 55 Patented July 1 0, 1973 3,745,224

8 Sheets-Sheet -L Patented July 10, 1973 3,745,224

8 Sheets-Sheet Patented July 10, 1973 8 SheetsSheet c Patented July 10, 1973 3,745,224

8 Sheets-Sheet Patented July 10, 1973 3,745,224

8 Sheets-Sheet 8 Ffgili '1 |8| I l I77 0 lllll 1 INH II I ws 1 ELECTRIC FURNACE INSTALLATION This invention relates generally to innovations and improvements in top-charge direct arc melting furnace installations which make possible a number of important structural, operational and safety advantages over conventional electric furnace installations of corresponding capacities.

In the construction of relatively small electric arc furnaces it is customary to pivotally support, in cantilever fashion, the removable roof structure together with the electrode supports, for swinging motion from the main furnace body or shell as generally illustrated in US. Pat. Nos. 1,276,586 and 2,396,663. In larger furnace sizes the back plate structure together with the electrode assembly and the roof supporting structure are sometimes supported from pillars carried on the furnace foundation as distinguished from the furnace platform. Top charging is accomplished by lifting this structure as a unit by a large cylinder and pivot means mounted on the foundation. This design has been found to create difficulty in establishing a satisfactory connection between the lifting device and the back plateroof structure. More commonly in the larger furnace sizes, the electrode furnace roof support structures are supported in cantilever fashion on the so-called back plate which in turn is directly supported on the furnace platform. In this more common design the lifted electrodes, roof and the electrode and roof supports together with the back plate are pivoted as a unit on a vertical axis for top charging in such manner that they can be swung to one side whereby the roof and electrodes clear the top of the furnace body. As this pivoting unit or structure is swung, due to its enormous weight, the center of gravity of the furnace assembly which includes the furnace body, shifts in such a way that the assembly would tip and fall in the direction the roof is swung unless positively restrained by suitable locking means.

While there are other important changes and innovations incorporated in electric arc furnaces embodying the present invention, the primary ones reside in providing a gantry structure by which a heavy furnace roof may be raised and removed without supporting it in cantilever fashion and/or without having to have the back plate assembly arranged to be pivoted or turned about a vertical axis. In the present invention the roof structure is supported from the upper horizontal section or superstructure of a gantry structure bridging the furnace and having upright side supports extending upwardly from platform members located on the opposite side of the furnace. In a preferred embodiment the furnace back plate assembly serves as one of the upright side supports and in smaller sized furnaces the back plate assembly may serve as the only upright side support in the gantry structure. The platform members are in several embodiments interconnected into a U- shaped platform frame by a cross member extending across the front of the furnace. The platform is normally arranged to be tilted in the direction of the ladle pit so as to thereby completely uncover the top of the furnace and pennit it to be directly charged in the usual manner. However, in certain instances the platform will be arranged to tilt in the opposite direction, i.e., toward the slag door. When the roof structure is in place closing the furnace body, the roofisupporting gantry and platform assembly, in several embodiments, is detachably locked or joined to the furnace body support structure so that the entire assembly may be tilted or rocked either in the direction of the slag pit for slag removal or in the direction of the ladle pit for pouring and discharging the molten contents of the furnace. The new construction provided by the present invention is such that the center of gravity of the furnace body can at all times be located so that the body tends to resist falling or tilting forward into the ladle pit, even when the roof has been lifted and tilted to its forwardmost position, or in its rear-most position in certain installations.

Accordingly, an important object of the invention is the provision of top-charge direct arc melting furnace installations in which the heavy furnace roof structures are no longer necessarily supported in cantilever fashion from the back plate assemblies, the back plate assembly is no longer rotatable about a vertical axis, and under all operational conditions the center of gravity of the furnace body may be located so that te furnace body has no tendency to fall or tip over into the ladle pit.

Another important object of the present invention is the provision of a top-charge direct arc melting furnace installation of the type described having the furnace roof supported from the superstructure of a gantry structure as above described thereby resulting in the following additional advantages: elimination of the expensive supporting structure and the operating and safety mechanisms required for rotating the back plate assembly about a vertical axis in order to swing the furnace roof to one side of the furnace body; utilizing the same hydraulic cylinder sub-assembly for both lifting and removing the furnace roof to uncover the furnace body and for tilting the closed furnace body in order to remove slag and discharge or pour its molten contents into ladles or other receptacles; permitting use of appreciably shorter electric current cables and bus bars allowing increased and more efficient power input and appreciable reduction in the movement and vibration of the bus bars and in the amounts of conductive materials required; effecting a reduction in the amount of stainless steel required for supporting the bus bars on the arms; substantially reducing the number, capacities and complexity of hydraulic and electrical components including hydraulic cylinders, pumps, valves, interlocks, switches, relays, etc.; making it practical to readily replace a furnace body with a new or reconditioned furnace shell or body; allowing an electric furnace to be located closer to the transformer room so as to decrease the floor area required for the furnace installation; increasing secondary cable life by reducing cable twisting; providing in one mechanism a means for raising the furnace roof thereby eliminating the usual separate roof lift structure; permitting a simplified and lighter back plate assembly; separating the tipping force of the furnace roof in its tilted position from the furnace body; and, permitting the furnace roof to be conveniently patched while it is in its tilted or removed position.

Certain other objects of the invention will be obvious and will appear hereinafter. For a more complete understanding of the nature and scope of the invention, reference may now be had to the following detailed description of preferred and illustrative embodiments thereof taken with the accompanying drawings, wherein:

FIG. 1 is a front elevational view taken in the direction of the pouring spout of a top-charge direct arc melting furnace installation constituting one embodiment of the invention;

FIG. 2 is a reduced top plan view of the electric furnace of FIG. 1;

FIG. 3 is an elevational view taken on line 3-3 of FIG. 1, with certain parts removed and showing the roof of the furnace raised and tilted to its fumacecharging position and indicating in broken lines the furnace body in its rearward tilted position for slag removal and in its forward tilted position for pouring;

FIG. 4 is an enlarged fragmentary detailed view taken on line 4-4 of FIG. 3 and showing one of the forward support legs for the furnace body;

FIG. 5 is a fragmentary detail view taken on line 5-5 of FIG. 4;

FIG. 6 is an enlarged fragmentary top plan view of the upper left-hand corner of FIG. 2 showing the interlocking mechanism;

FIG. 7 is a side elevational view taken on line 7-7 of FIG. 6;

FIG. 8 is a front elevational view similar to FIG. 1 of a modified electric furnace installation wherein the furnace roof and associated lifting and tilting structure are arranged to be pivoted on a hinge about an axis for-' wardly of the furnace while the furnace body is arranged to be tilted on a pair of supporting rockers;

FIG. 9 is a side elevational view taken on line 9-9 of FIG. 8 showing the furnace roof raised and tilted to its position in which the furnace is uncovered with the furnace body remaining in its upright position;

FIG. 10 is a front elevational view corresponding to FIG. 1 of another embodiment of the invention wherein the structure for supporting and tilting the furnace roof and the furnace body are mounted on separate rockers for tilting movement;

FIG. 11 is a side elevational view taken on line 11-11 of FIG. 10 and showing the roof and its supporting structure in its forward tilted position and showing the uncovered furnace body in its upright position;

FIG. 12 is a top plan view of the embodiment shown in FIGS. 10 and 11 with the cover closed;

FIG. 13 is an enlarged sectional detail view on line 13-13 of FIG. 12;

FIG. 14 is a front elevational view similar to FIG. 1 of still another embodiment wherein both the furnace body and the furnace roof and its supporting structure are hinge mounted for rotation about a common axis;

FIG. 15 is a view taken on line 15-15 of FIG. 14 showing the roof raised and in its forwardly tilted position the furnace thefurnace uncovered and in its upright position;

FIG. 16 is a top plan view of the embodiment shown in FIG. 14;

FIG. 17 is a front elevational view corresponding to FIG. 14 of an embodiment wherein the back plate assembly provides the only upright or upstanding gantry frame member;

FIG. 18 is a view taken on line 18-18 of FIG. 17 and corresponding to FIG. 15; and

FIG. 19 is a top plan view of the embodiment shown in FIGS. 17 and 18.

In the following detailed descriptions of preferred and illustrative embodiments of the invention certain parts and construction which are common to conventional electric furnace installations will not -be described in detail since the following description is intended to refer primarily to the novel features of construction provided by the present invention.

In FIGS. 1-3 a top-charge direct arc melting furnace is indicated generally at 5 comprising a conventional cylindrical furnace body 6 with a furnace roof 7 of conventional construction. The roof 7 is provided with collared openings 8-8 for receiving therethrough three electrode rods 10-10. The furnace -body 6 is supported from adjacent the bottom on a platform structure 11 which includes a pair of side l-beams 12-12 (FIG. 1) and a rear transverse box beam 14 interconnected in a U-configuration with the rear beam 14 pro- 15 jecting on opposite ends so as to provide support for corner formations indicated at 15 and 16 in FIG. 2. A lateral flange 17 of square outline projects from the shell of the furnace 6 and rests in bearing support relationship on the top surfaces of the interconnected beams 12-12 and 14.

The support platform 11 for the furnace body 6, comprised of the beams 12-12 and 14 and flange 17, is in turn supported from the underside by means of a four-point support system which includes a pair of vertical post members 18-18 mounted on the underside of the I-beams 12-12 at a location forwardly of the center of the furnace body 6 and a pair of support blocks 20 (FIG. 3) attached underside the rear transverse I-beam 14. The bottom bearing surface of each support block 20 is adapted to rest on any one of the three steps of a back rest 21 which is arranged to be reciprocably mounted in known manner so as to bring the upper, middle or lower step surfaces thereof directly underneath the back edge of the cooperating support block 20 as illustrated in FIG. 3. The shifting movement of each back rest 21 is provided by a remotely controlled double-acting hydraulic cylinder (not shown) in known manner.

The bottom ends of the vertical support posts 18 rest on rack segments 22-22. The posts 18 may be in the form of short lengths of an I-beam and on the inner edges each post 18 supports a member 23 having two depending gear teeth 24-24 (FIG. 5) separated by an intervening space which straddles a single upstanding tooth 25 which may be carried as part of one of the rack segments 22. It will be understood that the adjustable back rests 21 and racks 22 may be suitably supported on level metal plates mounted on the permanent masonry or concrete foundation of the pit for the electric furnace installation.

The manner in which the furnace body 6 is tilted to the rear when it is desired to remove slag and to the front when it is desired to pour its molten contents, will be described below in connection with the operation of the structure used to raise and tilt the furnace roof 7.

The furnace roof 7 is supported, raised and lowered from the upper hoirzontal section or superstructure of a gantry structure which fits over and down opposite sides of the furnace body 6 and roof 7. The superstructure is provided by a pair of parallel horizontal beams 26-26 with the opposite ends thereof being supported by pillar-like upright frame members on opposite sides of the furnace. The back plate assembly indicated generally at 27 of the furnace installation serves as the pi]- lar support on one side with the adjacent ends of the horizontal beam members 26 resting thereon. A pair of spaced vertical columns or posts 28-28 serve to support the ends of the beams 26 on the side of the furnace opposite the back plate assembly 27. The beams 26-26 are interconnected intermediate the upper ends of the posts 28 by means of tie member 30. The gantry structure that supports the furnace roof 7 is in turn supported on a U-shaped platform structure which is at the same level as the support platform 11 by which the furnace body 6 is supported from adjacent the bottom. The platform structure for supporting the back plate assembly 27 and the pillars or posts 28-28 includes a box-like beam 31 which extends underneath the back plate assembly 27, a box-like beam 32 which extends underneath the lower ends of the posts or pillars 28 and an interconnecting front member 33 which may also be a box-like structural member. It will-be seen from FIG. 2 that the members 31 and 32 together with member 33 comprise a generally U-shaped platform for supporting the gantry structure and interfitting the sides and front of the support platform structure 11 for the furnace body 6.

The U-shaped frame structure made up of the horizontal members 31, 32 and 33 and the bridge-like superstructure supported thereon are supported as a unit by means of a pair of spaced front-to-rear extending rocker segments 34-34 with the straight upper edges engaging the underside of the platform members 31 and 32 and with their arcuate lower edges resting on the straight horizontal upper surfaces of rail members 35-35.

Each rocker member 34 is provided on its inner face with a segment member 36-36 having gear teeth 37-37 (FIG. 3) on its arcuate bottom surface which mesh with the teeth 38-38 which stand up from the top surfaces of rack members 40-40. The rails 35-35 and adjoining rack members 40-40 are suitably supported in juxtaposed position on metal plates which rest on the permanent masonry or concrete emplacement for the electric furnace installation.

The furnace roof 7 is slung or supported at four points underneath the beams 26-26 by means of chains 41-41 (FIG. 1). The chains 41 pass in known manner over support and guide pulleys or sheaves (not shown) in accordance with conventional arrangement whereby the chains 41 may be actuated in unison to raise or lower roof 7. Since the lifting and lowering rigging for the roof 7 is known or conventional and does not form a part of the present invention it does not require further description.

The back plate assembly 27 is fixedly mounted on the horizontal platform member 31 and supports or houses much of the mechanism for raising and lowering the roof 7. The back plate assembly also houses the known and conventional mechanism for raising and lowering,

with precision control, the three electrodes -10 which are supported in cantilever fashion from the back plate assembly 27.

Desirably the roof of the furnace 7 is provided with a pair of stub posts 42-42 underneath each cross beam 26 in axial alignment with a pair of cups 43-43 carried by beams 26-26. When the roof 7 is raised by the chains 41 the posts 42 enter into the cups 43 whereby the furnace roof 7 is securely held against shifting on the underside of the beams 26 when lifted from the furnace 6. Since the roof securing mechanism may also be known or conventional and does not constitute a part of this invention, such mechanism will not be described in further detail.

In the operation of the electric arc furnace installation 5 several basic operating movements are required. Thus, the furnace roof 7 has to be lifted and moved off from the top of the furnace body 6 so that the furnace can be charged from the top while in the upright position. At the end of a run or melt the furnace body 6 must be first tilted to the rear so as to permit slag removal through the back and then it must be tilted forwardly so that the molten contents can be poured or discharged through the furnace spout 43 into a ladle. The mechanisms for permitting these basic movements will now be described.

In order to permit the raised furnace roof 7 to be removed from over the furnace body 6 without tilting the latter (as shown in solid line in FIG. 3) so as to permit the furnace to be top charged and also so as to permit the furnace body 6 to be tilted with the cover or roof covering the same, means are provided for detachably interlocking the U-shaped platform comprising members 31, 32 and 33 to the platform 11 that supports the furnace body 6. The key elements of this interlocking means are a pair of actuated locking pins 44 (FIG. 2) carried by the end formations 15 and 16 and which are adapted to project, in turn, into locking sockets provided therefor in furnace pit and openings in the rear ends of the side beams 31 and 32 of the furnace body supporting platform 11. Reference may be had to FIGS. 6 and 7 for a more detailed explanation of the releasable locking means and the manner of operation thereof.

During the course of a melt the electric furnace installation shown in FIGS. 1-7 operates in the usual manner. That is, electric current is supplied to the electrodes 10 so as to make an arc with the contents or charge within the furnace body 6 and the electrodes 10 are operated in a known manner so as to maintain the arc and bring about the melting of the charge. During this part of the melt cycle the parts will be in the position shown in solid line in FIGS. 1, 2 and 7. That is, the locking pins 44 will be interlocked or positioned so as to interlock the end formations 1S and 16 to the rear ends of the gantry support platform side members 31 and 32 respectively. The locus of the center of gravity of the furnace is such that the unit tends to tilt rearwardly and the block members 20 on the rear side of the furnace body platform 11 rest on the uppermost step of the backrest 21-21. The roof 7 will be lowered and resting in place on the top of the furnace body as shown in FIG. 1.

After the charge in the furnace has been melted and is ready to be poured it is first necessary to tilt the furnace body to the rear so as to discharge the slag. In order to do this the cylinders 56-56 are operated so as to take the load off from the back rests 21-21 and then these are actuated to the rear so as to bring the appropriate step underneath the blocks 20-20. when this adjustment has been made the cylinders 56-56 are contracted so as to allow the electric furnace to tilt rearwardly under its own weight until the blocks come to rest on the appropriate step of the back rest and then the slag is removed in the usual manner. When slag removal is complete, then the cylinders 56 are extended so as to tilt the furnace assembly forwardly so as to discharge the molten contents through the pour nozzle or spout 43.

Each locking pin 44 is slidably mounted for horizontal reciprocation in a pair of co-axial sleeve-like formations 45 and 46 (FIG. 7) integrally carried on the opposing inner faces of a vertical plate member 47 and an inclined rear plate member 48, respectively, forming part of the corner structures 15 and 16. Each pin 44 is of such length that it is appreciably longer than the maximum distance between the outside extremities of the sleeves 45 and 46. To the rear of each sleeve extension 46 there is a registering sleeve-like socket 50 which is formed in a stationary part of the pit structure 51 in which the electric furnace is positioned.

The rear end of the box-like side frame members 31 and 32 of the gantry support platform llll are provided with vertical plates 5252 each of which has an opening 49'that registers with the opening in the juxtaposed sleeve formation 45. The bottom edge of each plate 52 engages a ledge 59 on the bottom of the adjacent vertical plate 47 when the frame members are horizontal.

Each of the locking pins 44 is arranged to be actuated in either a forward or rear direction by means of a double-acting hydraulic cylinder 53, the piston rod 54 of which is connected with a fixed arm 55 that depends from the underside of the pin 44. The length of each pin 44 is such taken with the spacing of the associated sleeve formations 45 and 46, stationary socket t) and apertured plate 52, that the pin 44 may be moved to a rearmost position in which the rear end thereof will extend an appreciable distance into the socket 50 while the front end is located to the rear of the plate 52, and free and clear of the opening 49 therein. With the locking pins 44-44 in their rearmost position the side beams 31 and 32, as part of the support platform for the gantry, are free to tilt upwardly with respect to the corner structure forming part of the support platform ill for the furnace body 6. On the other hand, when the pins 44 are shifted forwardly, the rear ends thereof will lie wholly within the inclined plates 48 and sleeve-like formations 46 while the front ends thereof project substantially to the front of the vertical plates 52. in this relationship, which is shown in full line in FIG. 7, the side frame members 31 and 32 will be firmly interlocked with the corner structures 16 and 15 respectively, whereby these interlocked components or parts tilt simultaneously on tilting of the furnace body 6 and the cover 7 without being restrained by the pit emplacement structure 51.

While the locking pins 4444 will normally be in either the full-forward or full-rearward position, if for some reason (e.g., presence of a foreign object or failure of a cylinder 53) a pin 44 stops in an intermediate position, then the opposite ends will remain engaged in the plate opening 49 and the socket 50. This is a failsafe condition since one pin 44 in this intermediate position is adequate to safely interlock the pit structure 51, furnace platform structure 11 and gantry structure. The back face of the plate 48 and the front face of the emplacement structure 51 are forwardly inclined at the same angle and slightly spaced. This arrangement allows the spacing of these surfaces to be substantially reduced from what it would be if these surfaces were vertical, since back tilting of the furnace body 6 would result in interference if the opposing faces of plate 48 and of structure 51 were vertical.

A pair of hydraulic cylinders or rams 56-56 on opposite sides of the furnace provide the tilting action both for the furnace body 6 with the cover 7 lowered thereon and for the roof 7 independently of the furnace body as the latter remains in the upright position. The

connecting rod 57 of each hydraulic cylinder or ram 56 is pivotally connected by means of a pin 58 to one end of a rocker link 60 which is pivotally supported on a pin 61 extending through registering apertures in a bifurcated bracket 62. Each bracket 62 is carried on'the underside of the upper member of a frame beam 31 or 32.. The front end of each rocker link 60 is pivotally connected by a pin 63 to the lower end of a furnace roof operating rod 64 which is suitably interconnected with the conventional furnace roof lifting and lowering mechansim (not shown) so that when the rod 64 is pulled downwardly the furnace roof is raised, and conversely, when the rod 64 moves upwardly the roof 7 is lowered. Thus, at their upper ends the rods 64 may be connected to crank arms (not shown) on a rocker shaft carrying pulleys for winding and unwinding the furnace roof chains 41 in known manner. It is advantageous to have the rods 64 in tension rather than compression.

The rear end of each rocker link 60 has an upwardly extending formation 65 which provides a V-nose 66 for engaging in a corresponding V-shaped notch in the underside of the front end of the associated locking pin 44. The purpose of the engagement of the noses 66 in the notches in the locking pins 44 is two-fold. One purpose is to prevent relative movement of a pin 44 with respect to the frame member 31 or 32 whenever the locking member or bolt or pin 44 is fully removed from its stationary socket 50. In this connection the doubleacting cylinders 53 do not have sufficient power to overcome the interlocking of the nose 66 in the notch in case a cylinder 53 should be operated accidentally so as to tend to remove a pin 44. The other purpose of having the nose 66 on each rocker link 60 engage in the V-notch on the underside of the associated locking pin 44 is to establish that the locking pin 44 is moved sufficiently forward and then retained against shifting action during upward tilting of the furnace and roof structures as a unit. Further, in this connection, the interengaging surfaces of each V-notch and each nose 66 are cam surfaces and the adjacent end of each pin is beveled on the underside so that in operation each pin 44 is actuated to either its full-forward or full-rearward position.

When the locking pins 44 are shifted to the rear so as to be withdrawn from interengagement with the vertical plates 52, then the rocker links 60 are free to rotate clockwise as shown in FIG. 7 until the shoulder 67 on the formation 65 engages a stop or abutment member 68 mounted on the underside of the top plate of the associated frame member 31 or 32. Further extension of the piston rod 57 after shoulder 67 engages stop 68 produces tilting of the support platform for the gantry together with the already raised roof 7.

As a safety feature for locking the roof 7 in the raised position a latch 70 is provided which is pivotally mounted by a pin 71 at its upper end within an upwardly extending bifurcated bracket 72 on the upper side of a frame 83 (FIG. 6) on a bracket 74. The latch 70 is normally urged in a clockwise direction (as viewed in FIG. 7) by means of a spring 73 compressed between the vertical face of the depending support bracket 74 and a small clevis 75. The clevis 75 is pivotally connected to the rear of the latch 70 by means of a pin 76. The spring 73 fits over an end-threaded stem 77 on the clevis 75 and a lock nut 78 serves to adjust the extent to which the spring 73 urges the latch 70 in a clockwise direction. The latch 70 also carries a laterally projecting roller 80 which engages the inclined edge 81 of an elongated cam 79 mounted on the adjacent side of the I-beam 12 to control the latching and unlatching action of the latch 70 as the gantry structure supporting the roof 7 is raised and lowered respectively, independently of the furnace body 6.

Thus, when a rocker link 60 is in the position shown in broken line in FIG. 7, the engagement of the roller 80 with cam edge 81 prevents the latch 70 from having latching engagement with the ledge 82 until the gantry support platform including the frame member 31 or 32 tilts sufficiently for the roller 80 to allow the latch 70 to move into latching engagement. Conversely, when the furnace roof 7 is tilted rearwardly and lowered, each roller the engages its edge 81 and retracts its latch 70 from engagement with the ledge 82 thereupon allowing the rocker link 60 to rotate counter-clockwise while the roof 7 is allowed to settle in place on the furnace body 6.

When the locking pins 44-44 are withdrawn and the roof 7 has been raised off the furnace body 6, the tilt cylinders 56 on being further extended tilt the interconnected assembly which comprises (a) the U-shaped gantry support platform composed of frame members 31, 32 and 33, (b) the gantry structure that is supported thereon and composed of the back plate assembly 27, pillars 28 and the horizontal roof support members or beams 26-26, and (c) the roof 7 together with the electrodes 10 and the conductors 85-85 extending between the top of the back plate assembly 27 and the electrodes 10. The tilting movement is in the direction of the furnace pouring spout 43 and is under full control of the tilting cylinders 56 and the intermeshing of the teeth 37 on the rocker segments 36 and the rack teeth 38. In FIG. 3 the path of the center of gravity of the interconnected assembly (a), (b) and (0) during tilting is indicated by the line L. It is important to note that when the gantry-raised roof assembly is fully tilted to its forward-most position as shown in full line in FIG. 3, the center of gravity (c.g.,) thereof is to the rear of the vertical plane P through the points of support or contact between the rockers 34 and the racks 40. By virtue of this relationship there is no operative position in which the gantry raised roof assembly tends to fall over into the furnace pit. As previously indicated, the center of gravity of the furnace body 6 and of the complete furnace assembly is at all times well to the rear of the plane or line of support so as to maintain a fail-safe relationship.

With the roof raised and in its fully tilted position as shown in FIG. 3, it will be noted that the furnace body 6 is fully uncovered and chargeable in the usual manner from the top. After charging, the tilting cylinders 56 are retracted so as to bring the gantry structure back to a horizontal position over the furnace body 6 whereupon the roof 7 is lowered. Each cylinder 53 is then operated or actuated so as to shift the locking pins 66 forwardly so that each V-notch therein registers with a V-nose 49 when lifted into locking engagement thereby interlocking the gantry support platform for the gantry structure with the supporting platform 11 for the furnace body 6.

After the charge in the furnace body has been melted and the contents of the furnace are to be poured or removed, the first step is to extend the cylinders 56 sufficiently to take the load off the back rests 21. The next step is to operate the conventional cylinders (not moval. It will be seen that with each back rest 21 re tracted the furnace body 6 is supported partially by the posts 18, and partially by the tilting cylinders 56 through the interconnected and interlocked gantry and furnace body platform structures.

With the back rests 21 retracted to the desired position the tilting cylinders 56 are next actuated so as to rearwardly tilt the assembly as indicated in broken line in FIG. 3 and thereby permit the slag to be removed through the usual slag removal door (not shown) provided in the rear of the furnace body or shell. After the slag is removed, the tilting cylinders 56 are actuated so as to extend the connecting or piston rods 57 and tilt the entire furnace assembly forwardly to the pouring position as indicated by the broken line position of the spout 43 in FIG. 3. Support brackets 2929 (FIG. 2) on the inside of cross member 33 engage under the front edge of flange 17 when the assembly is thus tilted.

Before the assembly is returned from the pouring or discharge position to the upright position, each back rest 21 is moved forwardly so that the upper step thereof is in position to be engaged by its associated block 20. Then the tilt cylinders 56 are actuated so as to lower the upwardly tilted assembly until the blocks 20 once again rest on the upper steps of the back rests 21.

It will be apparent from the foregoing description of the installation 5 and the construction and operation thereof, that the operating mechanism is much simplier and requires substantially fewer parts and less material than conventional installations of comparable capacity. Only three hydraulic cylinder sub-assemblies are required, these being the usual cylinders (not shown) for actuating the back rests 21, the cylinders 53 for actuating the lock bars or pins 44 and the tilt cylinders 56.

In a well known furnace construction wherein to permit charging the furnace roof is swung to one side of the furnace body by rotating the back plate assembly about a vertical axis, the substantial weight of the furnace roof supported in cantilever fashion constitutes a considerable force that is more than sufficient to tip or turn the furnace body over unless positively restrained by suitable locking means. In the construction of the electric furnace installation 5 when the furnace roof is tilted to the position in which the furnace body is un-.

furnace body 6, and the body 6 is locked to the foundation by the pins 44. When the furnace roof 7 and its supporting structure and tilting mechanism are in the position in which the furnace roof closes the furnace body and the supporting platforms for the furnace body and the roof supporting gantry structure and support platform are interlocked, then, as pointed out above, the center of gravity of the resulting assembly will at all times be so located that the furnace body 6 tends to tilt rearwardly. Hence, there is no danger of the furnace body 6 and its contents ever tilting or falling forwardly into the pit.

As indicated above, a number of important advantages are attributable to the fact that the back plate assembly 27 does not have to pivot on a vertical axis as in conventional electric arc furnace installations. This feature permits the back plate assembly 27 to be positioned closer to the furnace body 6 on one side and closer to the transformer room on the other side. In view of this reduced spacing, the fixed conductors 85 to the electrodes can be made shorter thereby saving on materials and substantially reducing the vibration which inherently occurs when normal large operating currents are passing through these conductors. The flexible cables (not shown) which interconnect the conductors 85 to the transformer terminals can also be made shorter not only because of the closer spacing with respect to the transformer room, but also because the forward tilting movement required of the nonrotatable back plate assembly 27 (i.e., about 45") is less than the movement that is required in conventional designs where the back plate assembly is rotated approximately 57 about a vertical axis. Accordingly, an appreciable reduction in length of the flexible conductors or cables is permitted thereby resulting in a proportional reduction in cost of materials. Furthermore, the reductions in the lengths of the cables and of the fixed overhead conductors 85 reduces the power loss and thereby increases the efliciency of these cables and conductors in transmitting useful electrical energy to the electrodes 10. 1

Since the tilting movement required of the backplate assembly 27 is much less extensive than that involved in the rotation of a back plate assembly about a vertical axis in a conventional installation, less flexing and twisting action is imparted to the cables thereby substantially increasing the useful life thereof.

Furthermore, since the furnace body 6 is supported independently with respect to the rest of the installation, it is practical to remove one furnace body 6 and replace it with a new or reconditioned furnace body in a relatively short space of time. Such replacement is not ordinarily practical in prior conventional installations wherein the back plate assemblies are permanently interconnected with the furnace body support structure. Furthermore, with the furnace roof 7 in its fully tilted and removed condition, it is readily patcha ble whereas overhead patching is difficult in prior installations where the furnace roofs are not tilted to the side, but always suspended in the level or horizontal position. The deformation and settling which accompany the high stresses of cantilever support are also eliminated.

In FIGS. 8-9 and 14-16, two additional embodiments of the invention are shown wherein one pair of tilting cylinders is used in each embodiment for manipulating the furnace roof (i.e., lifting, tilting and lowering) and also for tilting the closed furnace body (i.e., rearwardly for slag removal and forwardly for pouring the furnace contents). In FIGS. 8 and 9 a furnace installation is indicated generally at 90 including a furnace body 91 and a roof 92. The furnace body 91 is supported by a support platform indicated generally at 93 which in turn is supported on a pair of rockers 94-94 which have gear teeth 95 for meshing engagement with gear teeth 96 on rail racks 97-97 each of which is suitably supported from the foundation for the installation.

At the rear corners of the platform 93, a pair of depending support blocks 90-98 are provided for resting on the top, middle or bottom steps of a pair of back rests -100 which are adjustable in front-to-rear direction as described in connection with FIGS. 1-3.

Each of the rockers 94 carries on the inner face thereof a forwardly projecting arm 101 for supporting at its outer end a shaft 102 that serves as the hinge pin for pivotally supporting a U-shaped frame 105 which serves to support the gantry superstructure 106 that carries the roof 92. The U-shaped frame 105 comprises side members 107, 108 interconnected at the front by a cross member 110. The gantry superstructure 106 corresponds generally to that shown and described in FIGS. 1-3. The front cross member 110 of the U- shaped frame 105 carries adjacent its opposite ends spaced depending apertured lugs 111-111 through which the hinge pins 102 extend.

The U-shaped frame 105 may be detachably locked or connected with the furnace support platform 93 by locking pins or bars 112-112 which are actuated by hydraulic cylinders (not shown) as described abovein connection with FIGS. 6 and 7.

By means of the hinge construction the U-shaped frame 105 together with the gantry-like superstructure 106, roof 92, and furnace electrodes 113-113 may be tilted as a unit so as to remove the raised roof 92 from the top of the furnace body 91 as illustrated in FIG. 9. The tilting cylinders 114-114 have piston or connecting rods 115 which are pivotally connected by pins 116 to apertured ears 117 depending from the underside of each side member 107 and 108 adjacent the rear end thereof.

In operation, after the roof 92 is raised the cylinders 114 serve to tilt the U-shaped platform 105 together with the gantry superstructure 106 supported thereon and roof 92 to the full furnace uncovering position as shown in FIG. 9. The furnace body 91 remains in its upright position and locked to the foundation by pins 112 while the U-shaped platform 105 tilts around the hinge pins 102.

After the furnace body 91 has been charged and the U-shaped platform 105 has been returned to the horizontal position and the roof 92 lowered onto the furnace body 91, the locking pins 44 are shifted forwardly so as to interlock the U-shaped platform 105 with the support platform 93 for the furnace body 91. The interlocked assembly is now in condition for the back rests 100 to be withdrawn when the charge is melted so that the covered or closed furnace body 91 may be tilted, first rearwardly for slag removal, and then forwardly for pouring the molten contents through the spout 118.

In FIGS. 10-13 a top-charge direct arc melting furnace installation is indicated at 120 which includes a furnace body 121 and a furnace roof 122. In this embodiment the furnace body 121 is supported on a pair of inner rockers 123-123 while the gantry support platform consists of side beams 124 and 125. These beams 124 and 125 which support the gantry superstructure indicated generally at 126 that in turn supports the furnace roof 122, are likewise supported on a pair of outer rockers 127-127. The side beams 124 and 125 may be releaseably interlocked or interconnected at their rear ends by locking pins or bars 128-128 with the opposite rear corners of the support platform 129 for the furnace body 121 in generally the same manner described above in connection with FIGS. 6 and 7.

ends of their piston rods 131 pivotally connected by pins'132 to apertured ears or brackets 133 on the undersides of the side beams 124 and 125 so that the roof 122 may be independently tilted off and lowered back on the furnace body 121 when the beams 124 and 125 are disconnected from the platform support 129 for the furnace body 121. However, when the side beams 124 and 125 are interlocked or interconnected with the furnace body support 121 by the locking bolts or pins 128 the entire assembly or installation tilts as a unit on both sets of rockers 123-123 and 127-127.

The second pair of tilt cylinders 134-134 have their piston rods 135-135 pivotally connected to the underside of the rear cross member 136 of the platform support 129. The cylinders 134 can be used to independently lower the furnace body 121 after a melt has been poured out through the spout 137 while the roof 122 remains raised and tilted. Accordingly, the empty furnace body 121 can be charged without having to first lower the roof 122 with the furnace body 121 and then re-raise it. Of course, the locking pins 128 have to be released before the body 121 can be independently lowered by the cylinders 134. In this method of operating the furnace 120, before the empty furnace body is returned to the upright position the retracted locking pins 128 must first be advanced so that the rear ends thereof will clear foundation. Thereafter when the furnace body 121 is upright the pins 128 will be retracted into interlocking position in the sockets provided therefore in the foundation. It will be understood that if after discharging a melt the roof 122 is lowered with the furnace body 121, the locking pins will not be retracted until the assembly has been returned to the upright posrtion.

In the embodiment of FIGS. -13 a separate pair of hydraulic cylinders 138-138 are provided for independently lifting and lowering the roof 122 from the furnace body 121. The cylinders 138 may be mounted on the back plate 139 with their upwardly projecting rods attached to the ends of the cables or chains 140-140. Each cable or chain 140 runs over a guide pulley 141 carried on the back plate and extends over the .furnace body to run over guide pulleys 142 and 143 and then turns downwardly to attach to a post 144 on the roof 122 which extends into a sleeve 145 on the underside of the gantry structure. A pair of shorter cables 149-149 attach to posts 146-146 extending into sleeves 147-147. Each shorter cable 149 passes over the adjacent pulley 142 and is then joined to the cable 140 at point 148.

It will be noted from FIG. 11 that the front projecting ends of the furnace platform support 129 and of the gantry side beams 124 and 125 may have stopengagement on foundation at 149 thereby positively limiting the extent of tilting of the furnace body 121 and the roof 122. It will be seen that the other embodiments may be provided with similar fail-safe stopengagement with the foundation.

In FIGS. 14-16 still another embodiment is shown wherein an electric furnace intallation 150 includes a furnace body 151 and a furnace roof 152. In this embodiment both the U-shaped platform 153 that supports the gantry superstructure 154 which in turn supports the furnace roof 152, and the platform 162 that supports the furnace body 151, are supported and hinged at the front of the installation 150 on piers 155 and 156. On their top surfaces the piers 155 and 156 each carries a pair of upstanding apertured support brackets 157-157 having hinge pins 158 extending therebetween.

The front cross member 160 on the U-shaped gantry support platform 153 carries adjacent its opposite ends depending lugs or ears 161-161 which are journaled on the support or hinge pins 158. The support platform 162 for the furnace body 151 carries a pair of forwardly projecting members 163-163 underneath the front cross member 164 thereof. These projecting members 163 are apertured at their front ends so as to be journaled on the hinge pin or shafts 158.

Conventional adjustable stepped back rests 165-165 (FIG. 15) are provided at the rear of the furnace assembly 150 for supporting the furnace body support platform 162 from underneath the back side in the usual manner.

The means for releasably interlocking the gantry support platform 153 with the furnace support platform 162 and for releasably interlocking the latter to the pit emplacement or foundation includes a pair of laterally shiftable locking pins 166-166 (FIG. 16). The cylinders for shifting the pins 166 are not shown. These pins are of such length that in one position their inner ends extend through apertures in stationary members 167-167 extending forwardly from the furnace pit emplacement while in their other position the outer ends of the pins extend through apertures in the rear ends of the side frame members 168 and 170 of the support platform 153. Thus, in one position the pins 166 interlock the furnace platform 162 with the pit emplacement through the members 167 while in the other position they interlock furnace platform with the gantry support platform 153. As previously described in connection with the locking pins 144 of the embodiment of FIGS. l-7, the locking pins 166 are of such length that they will fully engage the gantry support platform 153 before disengaging from their respective stationary members 167, and vice versa, thus establishing that the furnace platform 162 is firmly locked either to the gantry platform 153 or the foundation through members 167.

It will be seen that with the arrangement shown in 'FIGS. 14-16 a single set of tilt cylinders 171-171 may be used to tilt the U-shaped platform 153 and remove the raised furnace roof 152 from the furnace body 151 when the platform is unlocked or disconnected from the furnace body support platform 162. Similarly, when the U-shaped gantry support platform 153 is interlocked or interconnected with the furnace support platform 162 the entire assembly is tilted in unison. Both tilting actions take place on the axis of the hinge pins 158.

The embodiment shown in FIGS. 17-19 corresponds to the electric furnace installation of FIGS. 14-16 but with the gantry superstructure being supported from only one side of the furnace body by the back plate assembly.

Referring to FIGS. 17-19, an electric furnace installation indicated generally at 175 comprising a furnace body 176 and a furnace roof 177. In this embodiment, the gantry superstructure 178 is supported from the back plate assembly 180 which is in turn supported on the gantry support platform 181 provided by the foreand-aft beam 182. Both the platform 181 and the platform 183 that supports the furnace body 176, are supported and hinged at the front of the installation 175 on a pier 184 with the furnace body platform 133 being also supported and hinged on pier 185. On their top surfaces the piers 184 and 185 each carries a pair of upstanding apertured brackets 186-186 having hinge pins 187-187 extending therebetween. Pier 1841 also has a second pair of upstanding apertured brackets 188 thereon with a hinge pin 1911 extending therebetween.

The front cross portion 191 of the furnace body support platform 183 carries on the underside thereof a pair of apertured bracket members 192 which are journaled on the pins 187. Similarly, the front end of gantry support platform 181 has a pair of apertured bracket members 193-193 on the underside thereofjournaled on pin 190. By means of this hinge arrangement the roof 177 may be raised and tilted forwardly as shown in FIG. 18 independently of the furnace body 176, and the roof 177 and furnace body 176 may be tilted together forwardly and rearwardly.

Conventional adjustable stepped back rests 194-194 are provided at the rear of the furnace installation 175 for supporting the furnace body support platform 183 from underneath the back side thereof in the usual manner.

The means for releasably interlocking the gantry support platform 181 with the furnace support platform 183 and for releasably interlocking the latter to the furnace pit in emplacement or foundation, comprises a laterally shiftable locking pin 195 (FIG. 19) the conventional actuating cylinder for which is not shown. The pin 195 is of such length that in one of its extreme positions the inner end extends through an aperture in a stationary member 196 extending forwardly from the rear wall of the furnace pit emplacement while in its other extreme position the outer end extends through an aperture in the rear end of the fore and aft beam 182. Thus, in one position the pin 195 serves to interlock the furnace support platform 183 with the pit emplacement through the member 196 while in the other position the pin 195 interlocks the furnace support platform 183 with the gantry support platform 181. As previously described in connection with the locking pins 44 of the embodiment of FIGS. 1-7 and locking pins 166 of the embodiment of FIGS. 14-16, the locking pin 195 is of such length that it will fully engage the gantry support platform 181 before disengaging from the stationary member 196, and vice versa, the pin 195 will fully engage the stationary member 196 before disengaging from the gantry support platform 181, thus establishing that the furnace platform 183 is firmly locked at all times either to the gantry support platform 181 or to the foundation through the member 196.

The embodiment shown in FIGS. 17-19 is similar to that shown in FIGS. 111-113 in that one pair of tilt cylinders 197-197 is provided for tilting the furnace support platform 183 while a third tilt cylinder 19% is provided for tilting the gantry support platform 181. Accordingly, the furnace installation 175 may be operated in the same manner as described above in connection with the furnace 120 of FIGS. 10-13.

If desired, the embodiments of FIGS. 8 and 9, FIGS. 14-16 and FIGS. 17-19 may be equipped for independent roof raising and lowering by providing these embodiments with separate pairs of cylinders corresponding to the cylinders 138-138 and corresponding pulley-cable arrangements of F 108. 10-13.

It will be understood that certain changes may be made in the foregoing illustrative and preferred embodiments of the invention without departing from the spirit and scope thereof as defined in the appended claims. For example, while hydraulic power cylinders have been specified, other equivalent pneumatic, electric or mechanically powered motion imparting means of known type may be used.

What is claimed as new is:

1. In a top-charge direct arc melting furnace of the type having a body and a removable roof closing the body, the improvement of which comprises: means supporting said body in an upright position; a gantry including at least one upstanding gantry frame member disposed on one side of said body and supported independently of said furnace body for tilting movement about a generally horizontal axis and a gantry superstructure on said gantry frame member or members extending over said furnace; means carried by said gantry for lifting said removable roof; means for tilting said gantry independently of said furnace while said roof is lifted for top charging said body; and, means for tilting said body about a generally horizontal axis for pouring off molten material therein.

2. The improvement of claim 1 wherein said gantry and said body are interlocked for simultaneous tilting for pouring off molten material from said body.

3. The improvement of claim 1 wherein the composite center of gravity of said cantry and said roof remains to the rear of the line of support thereof during conjoint tilting thereof and wherein the composite center of gravity of said furnace body, roof and gantry remains to the rear of the line of support thereof during conjoint tilting, front being in the direction of pouring.

4. In a top-charge direct arc melting furnace of the type having a body, and a removable roof closing the body, the improvement which comprises: means supporting said body in an upright position; a gantry including at least one upstanding gantry'frame member disposed on one side of said body and supported independently of said body for tilting movement about a generally horizontal axis and a gantry superstructure on said gantry frame member or members extending over said furnace; means carried by said gantry for lifting said removable roof; means for tilting said gantry independently of said body while said roof is lifted for top charging said body; and, means for simultaneously tilting both said gantry and said body about a generally horizontal axis for pouring off molten material in the body.

5. In a top-charge direct arc melting furnace having a furnace body and a removable roof for closing said body, the improvement comprising: a furnace body support platform; means for supporting said furnace body support platform with said furnace body thereon; a gantry bridging said furnace body and roof; means for liftably supporting said roof from the superstructure of said gantry; a gantry support platform; means for tiltably supporting said gantry support platform with said gantry thereon; means for releasably interlocking said furnace body support platform and said gantry support platform for conjoint tilting about a generally horizontal axis; and, means for tilting said gantry support platform about a generally horizontal axis independently of said furnace body.

6. The improvement of claim 5 having separate means for tilting said furnace body support platform;

7. The improvement of claim 5 wherein said means for releasably interlocking comprises, at least one section on the rear of said furnace body support platform having a sleeve-like opening therein, a locking pin movably supported in said opening, said gantry support platform having a first socket juxtaposed to one end of said sleeve-like opening for receiving one end of said locking pin, a stationary second socket carried by the foundation for said furnace and juxtaposed to the other end of said sleeve-like opening for receiving the other end of said locking pin therein, and means operatively connected with said locking pin for moving the same in opposite directions in said sleeve-like opening whereby said locking pin has one position in which it is interlocked only with said first socket and a second position in which it is interlocked only with said second socket.

8. The improvement of claim 7 wherein said locking pin has a length sufficiently exceeding the length of said sleeve-like opening whereby before either opposite end of said locking pin withdraws from its associated socket the other opposite end is inserted in its associated socket.

9. In a top-charge direct arc melting furnace having a furnace body, a removable roof for closing said body, and a back plate assembly for operatively supporting the furnace electrodes, the improvement which comprises, a tiltable furnace body support platform for supporting said furnace body thereon, multi-pillar tiltable gantry means for supporting said roof therefrom and supported independently of said furnace body and said tiltable furnace body support platform bridging said body and including as one pillar means thereof said back plate assembly and having another pillar means thereof disposed on the side of said furnace body opposite from said back plate assembly, means for liftably supporting said roof from the superstructure of said gantry means, means for tilting said gantry means together with said roof independently of said furnace body through substantially the same path said gantry means moves when tilting with said furnace body for pouring its molten contents therefrom, and means for detachably locking said gantry means and said furnace body for conjoint tilting.

10. The improvement of claim 9 wherein said gantry means includes a platform portion having two parallel beams thereof extending front-to-rear along opposite sides of said furnace body support platform.

11. The improvement of claim 10 wherein said furnace body support platform has at least one portion thereof juxtaposed to one of the rear ends of said parallel beams and said locking means is operable to detachably lock said one portion to said adjacent beam rear end.

12. The improvement of claim 10 wherein said furnace body support platform has a generally rectangular outline and extends around said furnace body adjacent the bottom portion thereof, said gantry platform portion is generally U-shaped and tits in juxtaposed relationhsip around the front and two opposite sides of said furnace body support platform and is substantially colevel therewith when said furnace body support platform and said U-shaped platform portion are both horizontal and said furnace body is in its upright position, and said locking means detachably interconnects said furnace body support platform either to said U-shaped platform portion or to a fixed portion of the furnace foundation.

13. The improvement of claim 9 wherein hydraulic cylinder means is operatively connected with said tiltable gantry means for tilting said furnace body for pouring its molten contents while said body is detachably locked to said tiltable gantry means and for tilting said roof to its tilted removed position allowing top charging when said body is detached from said tiltable gantry means.

14. In a top-charge direct arc melting furnace installation having a furnace body, a removable roof for closing said body, and a back plate assembly for adjustably supporting the furnace electrodes and conductors thereto, the improvement comprising: means for independently supporting said furnace body in its upright position including a tiltable support platform attached to said furnace body adjacent the lower portion thereof; a gantry support platform having a pair of parallel beams extending along opposite sides of said furnace body support platform with a first parallel beam supporting said back plate assembly; a gantry mounted on said gantry support platform including said back plate assembly is a first pillar means on one side of said furnace body and second pillar means on the opposite side of said furnace body and supported on the second parallel beam and superstructure bridging said furnace body and supported on said pillar means; means for liftably supporting said. furnace roof on said superstructure; means for tiltably supporting said gantry support platform for tilting in a fore-and-aft direction generally parallel to said beams thereof independently of said furnace body; tilting means operatively connected with said gantry support platform; and, means for detachably locking said gantry support platform to said furnace body support platform for conjoint tilting of said furnace body together with said gantry and said furnace roof.

15. The improvement of claim 14 wherein said means for independently supporting said furnace body includes adjustable back rest means having a plurality of steps engageable by a rear portion of said furnace support platform.

16. The improvement of claim 14 wherein said furnace installation includes roof lifting and lowering mechanism operatively connected with said furnace roof and said tilting means comprises at least one hydraulic cylinder means which is operatively connected with both said roof lifting and lowering mechanism and with said gantry support platform whereby said roof is raised before said gantry support platform is tilted from its upright position and said roof is lowered after said gantry support platform has returned to its upright position.

17. The improvement of claim 14 wherein said furnace installation has roof lifting and lowering mechanism including an operating rod operatively connected with said furnace roof; and, said tilting means operatively interconnected with said gantry support platform comprises power cylinder means also operatively interconnected with said roof operating rod whereby said rod is first actuated by said power cylinder means to raise said roof before said power cylinder means operates to tilt said gantry support platform in a forward direction and whereby said power cylinder means operates to tilt said gantry support platform back to its horizontal position before it operates said rod to lower and close said furnace roof.

18. The improvement of claim 14 wherein said means for independently supporting said furnace body includes a pair of support posts located forwardly of the center of gravity of said furnace body empty or full, and said means for tiltably supporting said gantry support platform includes a pair of parallel spaced rockers extending in the fore-and-aft direction.

19. The improvement of claim 14 wherein said means for independently supporting said furnace body includes a pair of parallel spaced rockers extending in the fore-and-aft direction and disposed under the forward portion of said furnace body support platform and said means for tiltably supporting said gantry support platform comprises hinge means whereby said gantry support platform is hingedly supported by said means for independently supporting said furnace body for tilting on a hinge axis located in front of the lower portion of said furnace body.

20. The improvement of claim 14 wherein said means for independently supporting said furnace body includes a first pair of parallel spaced rockers extending in the fore-and-aft direction and disposed under the forward portion of said furnace body support platform and said means for tiltably supporting said gantry support platform comprises a second pair of parallel spaced rockers extending in the fore-and-aft direction and disposed under the forward portion of said gantry support platform.

21. The improvement of claim 14 wherein said means for independently supporting said furnace body comprises first hinge means having a fixed hinge part mounted forwardly of said furnace body and a pivotable hinge part connected to said furnace body support platform and said means for tiltably supporting said gantry support platform comprises second hinge means having a second fixed hinge part mounted forwardly of said furnace body and a second pivotable hinge part connected to said gantry support platform, the hinge axes of said first and second hinge means being coaxial.

22. The improvement of claim wherein: said means for liftably supporting said furnace roof includes an operating rod operatively connected with said furnace roof; said tilting means for said gantry support platform comprises first power cylinder means operatively interconnected with said roof operating rod through a rocker link rockably supported intermediate its ends on said gantry support platform with said first power cylinder means pivotally connected with said rocker link adjacent one end thereof and with said roof operating rod pivotally connected with said rocker link adjacent its opposite end whereby said rod is first actuated by said first power cylinder means to raise said roof before said first power cylinder means operates to tilt said gantry support platform and whereby said first power cylinder means operates to return said gantry support platform to its horizontal position before operating said roof operating rod to lower and close said furnace roof; and, said means for releaseably interlocking said furnace body support platform and said gantry support platform comprises, at least one section on the rear of said furnace body support platform having a horizontal sleeve-like opening therein, a locking pin supported in said opening for axial reciprocation therein, said gantry support platform having a first socket juxtaposed to one end of said sleeve-like opening for receiving one end of said locking pin, a stationary second socket carried by the furnace foundation and juxtaposed to the other end of said sleeve-like opening for receiving the other end of said locking pin therein and second power cylinder means operatively connected with said locking pin for axially sliding the same in opposite directions in said sleeve-like opening whereby said locking pin has one position in which it is interlocked only with said first socket and a second position in which it is interlocked only with said second socket.

23. The improvement of claim 22 wherein said locking pin has a notchin the underside adjacent said one end thereof and said rocker link has an upwardly turned nose on said one end thereof having mating locking engagement in said notch when said locking pin is in its said one position.

24. The improvement of claim 22 wherein latching means is mounted on said gantry support platform comprising a latch member having latching engagement with said other end of said rocker link when said roof is raised.

25. In a top-charge direct arc melting furnace having a furnace body, a removable roof for closing said body, and a back plate assembly for operatively supporting the furnace electrodes, the improvement which comprises, a tiltable furnace body support platform for supporting said furnace body thereon, single-pillar tiltable gantry means for supporting said roof from a superstructure spanning said body and having as the pillar means thereof said back plate assembly said gantry means being supported independently of said furnace body and said tiltable furnace body support platform, means for liftably supporting said roof from said gantry superstructure, means for tilting said gantry means on a generally horizontal axis together with said roof independently of said furnace body through substantially the same path said gantry means moves when tilting with said furnace body for pouring its molten contents therefrom, and means for detachably locking said gantry means and said furnace body for conjointtilting about a generally horizontal axis.

UNITED STATES PATENT OFFICE QETIFICATE OF CORRECTION Patent No 3,745,22u Dated July 10, 1973 invent fls) Victor H. Ames It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 20, "te" should be --the.

Column 3, line 53, after "tion" insert --with--.

Column 3, line 53, after "furnace" delete "thefurnaoe".

! Column 9, line 15, delete "the'fand insert -8o--.

Column l6, line 27, "cantry" should be --gantry--.

Column 18, line 20, "is" should be --as--.

Signed and sealed this 8tlr day of January 1974.

Attest:

EDWAROMJLETCHERJR. RENE D. TEGTMEYER Attestlng Officer Acting Commissioner of Patents FoRM PO-105O (10- 69) USCOMM-DC scan-P09 7 0 V U.5. GOVERNMENT PRINUNG OFFICE 1 I959 0-366-33L 

1. In a top-charge direct arc melting furnace of the type having a body and a removable roof closing the body, the improvement of which comprises: means supporting said body in an upright position; a gantry including at least one upstanding gantry frame member disposed on one side of said body and supported independently of said furnace body for tilting movement about a generally horizontal axis and a gantry superstructure on said gantry frame member or members extending over said furnace; means carried by said gantry for lifting said removable roof; means for tilting said gantry independently of said furnace while said roof is lifted for top charging said body; and, means for tilting said body about a generally horizontal axis for pouring off molten material therein.
 2. The improvement of claim 1 wherein said gantry and said body are interlocked for simultaneous tilting for pouring off molten material from said body.
 3. The improvement of claim 1 wherein the composite center of gravity of said cantry and said roof remains to the rear of the line of support thereof during conjoint tilting thereof and wherein the composite center of gravity of said furnace boDy, roof and gantry remains to the rear of the line of support thereof during conjoint tilting, front being in the direction of pouring.
 4. In a top-charge direct arc melting furnace of the type having a body, and a removable roof closing the body, the improvement which comprises: means supporting said body in an upright position; a gantry including at least one upstanding gantry frame member disposed on one side of said body and supported independently of said body for tilting movement about a generally horizontal axis and a gantry superstructure on said gantry frame member or members extending over said furnace; means carried by said gantry for lifting said removable roof; means for tilting said gantry independently of said body while said roof is lifted for top charging said body; and, means for simultaneously tilting both said gantry and said body about a generally horizontal axis for pouring off molten material in the body.
 5. In a top-charge direct arc melting furnace having a furnace body and a removable roof for closing said body, the improvement comprising: a furnace body support platform; means for supporting said furnace body support platform with said furnace body thereon; a gantry bridging said furnace body and roof; means for liftably supporting said roof from the superstructure of said gantry; a gantry support platform; means for tiltably supporting said gantry support platform with said gantry thereon; means for releasably interlocking said furnace body support platform and said gantry support platform for conjoint tilting about a generally horizontal axis; and, means for tilting said gantry support platform about a generally horizontal axis independently of said furnace body.
 6. The improvement of claim 5 having separate means for tilting said furnace body support platform.
 7. The improvement of claim 5 wherein said means for releasably interlocking comprises, at least one section on the rear of said furnace body support platform having a sleeve-like opening therein, a locking pin movably supported in said opening, said gantry support platform having a first socket juxtaposed to one end of said sleeve-like opening for receiving one end of said locking pin, a stationary second socket carried by the foundation for said furnace and juxtaposed to the other end of said sleeve-like opening for receiving the other end of said locking pin therein, and means operatively connected with said locking pin for moving the same in opposite directions in said sleeve-like opening whereby said locking pin has one position in which it is interlocked only with said first socket and a second position in which it is interlocked only with said second socket.
 8. The improvement of claim 7 wherein said locking pin has a length sufficiently exceeding the length of said sleeve-like opening whereby before either opposite end of said locking pin withdraws from its associated socket the other opposite end is inserted in its associated socket.
 9. In a top-charge direct arc melting furnace having a furnace body, a removable roof for closing said body, and a back plate assembly for operatively supporting the furnace electrodes, the improvement which comprises, a tiltable furnace body support platform for supporting said furnace body thereon, multi-pillar tiltable gantry means for supporting said roof therefrom and supported independently of said furnace body and said tiltable furnace body support platform bridging said body and including as one pillar means thereof said back plate assembly and having another pillar means thereof disposed on the side of said furnace body opposite from said back plate assembly, means for liftably supporting said roof from the superstructure of said gantry means, means for tilting said gantry means together with said roof independently of said furnace body through substantially the same path said gantry means moves when tilting with said furnace body for pouring its molten contents therefrom, and means for detachably locking said gantry means And said furnace body for conjoint tilting.
 10. The improvement of claim 9 wherein said gantry means includes a platform portion having two parallel beams thereof extending front-to-rear along opposite sides of said furnace body support platform.
 11. The improvement of claim 10 wherein said furnace body support platform has at least one portion thereof juxtaposed to one of the rear ends of said parallel beams and said locking means is operable to detachably lock said one portion to said adjacent beam rear end.
 12. The improvement of claim 10 wherein said furnace body support platform has a generally rectangular outline and extends around said furnace body adjacent the bottom portion thereof, said gantry platform portion is generally U-shaped and fits in juxtaposed relationhsip around the front and two opposite sides of said furnace body support platform and is substantially co-level therewith when said furnace body support platform and said U-shaped platform portion are both horizontal and said furnace body is in its upright position, and said locking means detachably interconnects said furnace body support platform either to said U-shaped platform portion or to a fixed portion of the furnace foundation.
 13. The improvement of claim 9 wherein hydraulic cylinder means is operatively connected with said tiltable gantry means for tilting said furnace body for pouring its molten contents while said body is detachably locked to said tiltable gantry means and for tilting said roof to its tilted removed position allowing top charging when said body is detached from said tiltable gantry means.
 14. In a top-charge direct arc melting furnace installation having a furnace body, a removable roof for closing said body, and a back plate assembly for adjustably supporting the furnace electrodes and conductors thereto, the improvement comprising: means for independently supporting said furnace body in its upright position including a tiltable support platform attached to said furnace body adjacent the lower portion thereof; a gantry support platform having a pair of parallel beams extending along opposite sides of said furnace body support platform with a first parallel beam supporting said back plate assembly; a gantry mounted on said gantry support platform including said back plate assembly is a first pillar means on one side of said furnace body and second pillar means on the opposite side of said furnace body and supported on the second parallel beam and superstructure bridging said furnace body and supported on said pillar means; means for liftably supporting said furnace roof on said superstructure; means for tiltably supporting said gantry support platform for tilting in a fore-and-aft direction generally parallel to said beams thereof independently of said furnace body; tilting means operatively connected with said gantry support platform; and, means for detachably locking said gantry support platform to said furnace body support platform for conjoint tilting of said furnace body together with said gantry and said furnace roof.
 15. The improvement of claim 14 wherein said means for independently supporting said furnace body includes adjustable back rest means having a plurality of steps engageable by a rear portion of said furnace support platform.
 16. The improvement of claim 14 wherein said furnace installation includes roof lifting and lowering mechanism operatively connected with said furnace roof and said tilting means comprises at least one hydraulic cylinder means which is operatively connected with both said roof lifting and lowering mechanism and with said gantry support platform whereby said roof is raised before said gantry support platform is tilted from its upright position and said roof is lowered after said gantry support platform has returned to its upright position.
 17. The improvement of claim 14 wherein said furnace installation has roof lifting and lowering mechanism including an operating rod operatively connected with said furnace roof; and, said tilting means operatively interconnected with said gantry support platform comprises power cylinder means also operatively interconnected with said roof operating rod whereby said rod is first actuated by said power cylinder means to raise said roof before said power cylinder means operates to tilt said gantry support platform in a forward direction and whereby said power cylinder means operates to tilt said gantry support platform back to its horizontal position before it operates said rod to lower and close said furnace roof.
 18. The improvement of claim 14 wherein said means for independently supporting said furnace body includes a pair of support posts located forwardly of the center of gravity of said furnace body empty or full, and said means for tiltably supporting said gantry support platform includes a pair of parallel spaced rockers extending in the fore-and-aft direction.
 19. The improvement of claim 14 wherein said means for independently supporting said furnace body includes a pair of parallel spaced rockers extending in the fore-and-aft direction and disposed under the forward portion of said furnace body support platform and said means for tiltably supporting said gantry support platform comprises hinge means whereby said gantry support platform is hingedly supported by said means for independently supporting said furnace body for tilting on a hinge axis located in front of the lower portion of said furnace body.
 20. The improvement of claim 14 wherein said means for independently supporting said furnace body includes a first pair of parallel spaced rockers extending in the fore-and-aft direction and disposed under the forward portion of said furnace body support platform and said means for tiltably supporting said gantry support platform comprises a second pair of parallel spaced rockers extending in the fore-and-aft direction and disposed under the forward portion of said gantry support platform.
 21. The improvement of claim 14 wherein said means for independently supporting said furnace body comprises first hinge means having a fixed hinge part mounted forwardly of said furnace body and a pivotable hinge part connected to said furnace body support platform and said means for tiltably supporting said gantry support platform comprises second hinge means having a second fixed hinge part mounted forwardly of said furnace body and a second pivotable hinge part connected to said gantry support platform, the hinge axes of said first and second hinge means being co-axial.
 22. The improvement of claim 5 wherein: said means for liftably supporting said furnace roof includes an operating rod operatively connected with said furnace roof; said tilting means for said gantry support platform comprises first power cylinder means operatively interconnected with said roof operating rod through a rocker link rockably supported intermediate its ends on said gantry support platform with said first power cylinder means pivotally connected with said rocker link adjacent one end thereof and with said roof operating rod pivotally connected with said rocker link adjacent its opposite end whereby said rod is first actuated by said first power cylinder means to raise said roof before said first power cylinder means operates to tilt said gantry support platform and whereby said first power cylinder means operates to return said gantry support platform to its horizontal position before operating said roof operating rod to lower and close said furnace roof; and, said means for releaseably interlocking said furnace body support platform and said gantry support platform comprises, at least one section on the rear of said furnace body support platform having a horizontal sleeve-like opening therein, a locking pin supported in said opening for axial reciprocation therein, said gantry support platform having a first socket juxtaposed to one end of said sleeve-like opening for receiving one end of said locking pin, a stationary second socket carried by the furnace founDation and juxtaposed to the other end of said sleeve-like opening for receiving the other end of said locking pin therein and second power cylinder means operatively connected with said locking pin for axially sliding the same in opposite directions in said sleeve-like opening whereby said locking pin has one position in which it is interlocked only with said first socket and a second position in which it is interlocked only with said second socket.
 23. The improvement of claim 22 wherein said locking pin has a notch in the underside adjacent said one end thereof and said rocker link has an upwardly turned nose on said one end thereof having mating locking engagement in said notch when said locking pin is in its said one position.
 24. The improvement of claim 22 wherein latching means is mounted on said gantry support platform comprising a latch member having latching engagement with said other end of said rocker link when said roof is raised.
 25. In a top-charge direct arc melting furnace having a furnace body, a removable roof for closing said body, and a back plate assembly for operatively supporting the furnace electrodes, the improvement which comprises, a tiltable furnace body support platform for supporting said furnace body thereon, single-pillar tiltable gantry means for supporting said roof from a superstructure spanning said body and having as the pillar means thereof said back plate assembly said gantry means being supported independently of said furnace body and said tiltable furnace body support platform, means for liftably supporting said roof from said gantry superstructure, means for tilting said gantry means on a generally horizontal axis together with said roof independently of said furnace body through substantially the same path said gantry means moves when tilting with said furnace body for pouring its molten contents therefrom, and means for detachably locking said gantry means and said furnace body for conjoint tilting about a generally horizontal axis. 